1. Field of the Invention
The present invention relates to a battery pack, and more particularly to a multi-battery pack system, a method for controlling the same, and a battery pack, in which the battery packs can be set as a master battery pack and slave battery packs by themselves.
2. Description of the Prior Art
Generally, portable electronic devices including portable telephones, laptop computers, digital cameras and the like, have used a battery pack, which contains a plurality of rechargeable cells, as an electric power source.
Recently, battery packs have been connected in parallel to supply sufficient capacity of electricity to a portable electronic device in order to secure a stable operation of the portable electronic device. In addition, a multi-battery pack system has been proposed to correspond to a variety of portable electronic devices.
As the multi-battery pack system has been realized in which a variable number of the battery packs can be contained, there is a problem in that it is difficult to control the multi-battery pack system.
In order to solve the problem, Japanese Patent No. 3405526 discloses an electric source using multi-battery packs. In the electric source using the multi-battery packs, each of the multi-battery packs has a plurality of cells and a circuit for checking charge and discharge state of the cells or controlling charge and discharge of the cells. The electric source using the multi-battery packs includes a master battery pack and a plurality of slave battery packs. The master battery pack requests that the slave battery packs transmit data indicating the charge and discharge state with communication, manages the entire data, identifies the charge and discharge state so as to transmit a command, and controls the charge and discharge of the slave battery packs. The slave battery packs transmits data indicating the charge and discharge state in response to the request of the master battery pack, and receives the command from the master battery pack to carry out the charge and discharge thereof.
According to the conventional art, the master battery pack controls the charge and discharge of the plural slave battery packs. When the master battery pack is detached from the electronic device or fully discharged, the master battery pack does not normally operate. In this case, there is a problem in that it is impossible to control the slave battery pack as well as the master battery pack. Further, even when plural battery packs are set as the master battery pack by mistake, a corresponding multi-battery pack system cannot normally operate.
Further, in the case where the setting position of the master battery pack is determined, if the master battery pack does not normally operate because of the detachment from the electronic device or the complete discharge, it is impossible to control the slave battery packs as well as the master battery pack.
Accordingly, the development of technology is required to enable the battery packs for the multi-battery pack system to be set as a master battery pack and slave battery packs automatically.
Further, the development of technology is required to the battery packs to be set as a master battery pack and slave battery packs so that the multi-battery pack system can normally operate, even though the master battery pack is absent or malfunctions.